Modulation of pacemaker activity in sheep cardiac Purkinje fibers by stimulation of β-adrenoceptor subtypes

The electrophysiological effects mediated by ₁- and ₂- in spontaneously active sheep cardiac Purkinje fibers were investigated using the non-selective agonist (–)-isoproterenol (IPN) and the selective agonists (–)-noradrenaline (₁) and procaterol (₂) in the absence and presence of the selective antagonists bisoprolol (₁) and ICI 118,551 (₂).IPN (0.01 mol/l) increased the spontaneous rate by 54% and the slope of diastolic depolarization by 68% of the respective control values. Further, IPN increased the action potential duration at –20 mV (APD –20 mV) from 96 to 154 ms, reduced the APD –70 mV by 17% and the duration of the diastole by 39% and slightly hyperpolarized the maximum diastolic potential. These effects were partially inhibited by ICI 118,551 (0.03 mol/l), diminished by bisoprolol (0.1 mol/l) and almost completely blocked by the combination of both antagonists. Concentration response curves of IPN were influenced by the selective antagonists as follows: ICI 118,551 (0.03 mol/l) shifted the curves to the right by 0.2–0.4 log units and increased the slope factor. Bisoprolol (0.1 mol/l) induced a greater shift to the right by 1.1–1.5 log units. Combination of bisoprolol with ICI 118,551 shifted the curves to the right by 1.5–1.7 log units.Noradrenaline (0.3 mol/l) elicited similar actions as IPN. Bisoprolol (0.1 mol/l) shifted the concentration response curves of noradrenaline to the right by 1.1–1.9 log units. Actions of procaterol (0.1 mol/l) were weak, attained only 15–35% of the maximal effects of IPN and could be blocked by ICI 118,551 (0.03 mol/l).These results show that the increase of pacemaker activity induced by catecholamines in sheep cardiac Purkinje fibers is predominantly mediated by stimulation of ₁. However, contribution of ₂ mediated effects could be demonstrated.Supported by Ministerium für Wissenschaft und Forschung, Nordrhein-Westfalen, Projekt-Nr, 40008786.     

Überlegungen und Hochrechnungen zur Epidemiologie des „Acquired Immunodeficiency Syndrome“ in der Bundesrepublik Deutschland

Zusammenfassung Aufgeschlüsselt nach Bevölkerungskollektiven mit unterschiedlichen sexuellen Verhaltensweisen wird anhand der bisher bekannten bzw. größenordnungsmäßig abgeschätzten epidemiologischen Daten des Acquired Immunodeficiency Syndrome eine Hochrechnung der Morbiditäts- und Mortalitätsziffern für die Bundesrepublik Deutschland mittels Computer-Simulation vorgenommen; danach könnten in den nächsten 15 Jahren bis ca. 41 000 Personen erkranken. Die Bedeutung der weiblichen Prostituierten und der männlichen Bisexuellen als Vektoren der Infektion aus den bisherigen Risikogruppen in Bevölkerungsteile mit ausschließlich heterosexuellen Verhaltensweisen, der Einfluß infektiologischer Schutzmaßnahmen sowie der Effekt sexueller Verhaltensänderungen breiter Bevölkerungsschichten kann mit diesem Programm ebenfalls untersucht werden.

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Considerations and simulations regarding the epidemiology of the acquired immunodeficiency syndrome in the federal republic of Germany

Summary A computer simulation of the morbidity and mortality rates of the Acquired Immunodeficiency Syndrome in the Federal Republic of Germany was performed. Since sexual intercourse is the main mode of transmission, the population was divided into six groups with different sexual behaviour. In several variations of the program it is demonstrated that during the next 15 years up to 41,000 AIDS patients can be expected. The importance of female prostitutes and male bisexuals as vectors who may transmit the infection into exclusively heterosexual groups is shown. Using this program, the effect of prophylaxis against infection as well as of changes of sexual behaviour within the population at large can also be examined.

     

The ability of heat stress and metabolic preconditioning to protect primary rat cardiac myocytes

Primary rat cardiocytes were subjected to either thermal preconditioning for 30 min at 43°C or 20 min metabolic preconditioning (10 mM deoxyglucose, 20 mM lactate, pH 6.5). Eighteen hours later cells were analysed either for hsp 70i expression or subjected to a subsequent lethal heat stress or simulated ischaemia (10 mM deoxyglucose, 20 mM lactate, 0.75 mM sodium dithionite, 12 mM potassium chloride, pH 6.5) for 2 hours and assessed for survival by trypan blue exclusion.Hsp 70i was induced over 100 fold by thermal preconditioning and 30 fold by metabolic preconditioning (p<0.001, p<0.05), hsp 90 was induced 2.71 fold and 2.24 fold (p<0.001, p<0.001) by thermal and metabolic preconditioning respectively, while hsp 60 was not induced by either treatment. Preconditioned cultures had improved survival against subsequent lethal heat stress or simulated ischaemia: Thermal preconditioning reduced death from 69.22% to 52.46% upon subsequent lethal heat stress and from 49.13% to 36.66% upon subsequent lethal simulated ischaemia. Metabolic preconditioning reduced cell death from 51.29% to 33.8% against subsequent lethal heat stress, and from 69.09% to 55.61% upon subsequent lethal simulated ischaemia. A second marker of cell death, the release of lactate dehydrogenase activity into the culture media, was reduced to 65% and 60% of control values for thermally preconditioned cells subjected to lethal heat or lethal simulated ischaemia respectively. Metabolically preconditioned cells demonstrated lactate dehydrogenase activity of 59% and 51% that of control values, when subjected to lethal heat or lethal simulated ischaemia respectively.Abbreviations hsp heat stress protein - hsp 70i inducible 70 kDa heat stress protein - LDH lactate dehydrogenase - PBS phosphate buffered saline     

Expression of interferon-γ and tumor necrosis factor-α in bone marrow T cells and their levels in bone marrow plasma in patients with aplastic anemia

Immune-mediated stem cell damage has been postulated to be responsible for disease initiation and progression in aplastic anemia (AA). It is hypothesized that T lymphocytes play a major role in destroying the bone marrow (BM) stem cells of AA patients by infiltrating the BM and secreting excessive levels of anti-hematopoietic cytokines, interferon-gamma (IFN-), and tumor necrosis factor-alpha (TNF-). We undertook this study to assess the pathogenic significance of anti-hematopoietic cytokines such as IFN- and TNF- in BM T cells and plasma of AA patients. Significantly elevated levels of IFN- and TNF- were found in the BM plasma of AA patients compared to controls (p=0.05 and 0.006, respectively). Intracellular IFN- and not TNF- in BM CD3⁺ T cells of AA patients was significantly higher compared to controls (p=0.04 and p=0.2, respectively). A follow-up analysis of expression of these cytokines in BM T cells and their levels in BM plasma in five AA patients before and 180 days (6 months) after antithymocyte globulin (ATG) and cyclosporin A (CsA) therapy showed a decline 180 days after therapy compared to pre-therapy. We thus conclude that increased production of both IFN- and TNF- in the BM may contribute to disease pathogenesis in AA and ATG therapy may induce hematological remission by suppressing the elevated levels of IFN- and TNF- in AA BM.     

Incidence of strains producing extended spectrum β-lactamases in Argentina

Summary The incidence of strains producing transferable -lactamases capable of hydrolyzing third generation cephalosporins or aminothiazole-oximino substituted monobactams in five Buenos Aires hospitals during a four month period was studied. These enzymes were categorized by 1) MIC 1 mg/l for third generation cephalosporins; 2) MIC < 0.06 mg/l for third generation cephalosporins combined with clavulanic acid or sulbactam; 3) sensitivity to imipenem or cephamycins (excluding permeability mutants); and 4) transferable resistance by conjugation. -lactamases hydrolyzing aminothiazole-oximino substituted monobactams were produced by 17.2% of Enterobacteriaceae from intensive care unit patients; 3.6% from inpatients of other units and 1.2% from outpatients. Producers were mainlyKlebsiella spp. (45/46) resistant to aminoglycosides (most of them AAC 3 — AAC 6 producers). Three strains had a an isoelectric point of 6.0, two of 6.5 and three of 7.7. TEM-1 -lactamase (isoelectric point 5.4) was detected in 6/8 strains. An inocolum effect was observed in 40/46 strains. AKlebsiella pneumoniae strain preserved since 1982 also produced a transferable -lactamase hydrolyzing aminothiazole-oximino substituted monobactams.

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Vorkommen von Bakterienstämmen mit erweitertem Breitspektrum -Laktamasen in Argentinien

Zusammenfassung Während einer Zeit von vier Monaten wurde an fünf Krankenhäusern in Buenos Aires nach dem Vorkommen von Stämmen mit Bildung übertragbarer -Laktamasen gesucht, die Cephalosporine der dritten Generation oder aminothiazol-oximino-substituierte Monobaktame hydrolysieren. Kriterien für die Selektion dieser Enzyme waren 1) MHK-Werte von 1 mg/l für Cephalosporine der dritten Generation; 2) MHK-Werte von < 0,06 mg/l für Drittgenerationscephalosporine in Kombination mit Clavulansäure oder Sulbactam; 3) Empfindlichkeit gegenüber Imipenem oder Cephamycinen; 4) Resistenz übertragbar. Zur Bildung von -Laktamasen mit hydrolytischer Aktivität gegen Aminothiazol-oximinosubstituierte Monobaktame waren 17,2% der Enterobacteriaceae-Isolate von Intensivpflegepatienten befähigt, 3,6% der Isolate von Patienten von anderen Stationen und 1,2% der Isolate von ambulanten Patienten. Die meisten der Stämme, die diese Enzyme bildeten (45/46), waren aminoglykosidresistenteKlebsiella spp. (Synthese von AAC 3-AAC 6). Der isoelektrische Punkt lag bei drei Enzymen bei 6,0, in zwei Fällen bei 6,5 und in drei Fällen bei 7,7. Sechs von acht Stämmen bildeten TEM-1 -Laktamase. Bei 40 der 46 Stämme wurde ein Inokulumeffekt festgestellt. Die Bildung übertragbarer -Laktamasen mit hydrolytischer Wirkung gegen Aminothiazolyl-oximino-substitutierte Monobaktame wurde in einem bereits seit 1982 gelagertenKlebsiella pneumoniae-Stamm nachgewiesen.

     

Differential survival of cell subpopulations in spheroids after treatment with bleomycin

Summary The cytotoxic effect of bleomycin (BLM) on Chinese hamster V79-cells grown as spheroids is compared to that on monolayer cultures in exponential vs. plateau phase of growth. Cells treated as intact spheroids with BLM (50 g/ml for 1 h) are more sensitive than monolayer cultures. Cell subpopulations derived from different zones of the spheroids survive BLM-treatment to different degrees: When treated as single cells in suspension, the formerly outer cells are less affected than the inner cells. Within intact spheroids, however, progressive cellular resistance with increasing distance from the outer rim is found.     

Pyruvate carboxylase deficiencies: Complementation studies between “French” and “American” phenotypes in cultured fibroblasts

Pyruvate carboxylase (PC) deficiencies (McKusick 26615) are heterogeneous clinically and biochemically. We performed a complementation study with fibroblast strains from seven patients, (four patients with French phenotype, two patients with American phenotype, one patient with biotin responsive multiple carboxylase deficiency, MCD). The six isolated pyruvate carboxylase mutants (two cross-reacting material CRM –ve and four CRM +ve) failed to complement each other, but did complement a form of biotin responsive MCD.     

The value and limitations of gastroscopy in the diagnosis of antral lesions

Conclusions 1. Gastroscopy is often of great value in the differential diagnosis of the gastric antrum observed radiologically to be spastic, rigid, and deformed, for confirming an X-ray diagnosis of antral lesion (neoplasm, ulcer, gastritis), in the differential diagnosis of antral ulcers, and in correcting an erroneous X-ray interpretation of a benign lesion.2. The gastroscopic method is limited when technical factors prevent adequate observation of the antrum (failure of peristalsis, antral adhesions, overinflation of the stomach), by the misinterpretation of pyloric closure when it occurs proximal to the true pylorus, hiding a distal antral lesion, and in distally located ulcers and neoplasms.3. Gastroscopy is a valuable adjunct to radiology in the differential diagnosis of antral lesions and should be done in all such patients.     

Die Bildungsarten,Entwicklungsstadien und Wachstumsstufen des Carcinoms am Beispiel der Epithelproliferationen der Brustdrüse

Zusammenfassung Am Beispiel früher (1937) schon beschriebener Drüsenkrebse und am Beispiel neu untersuchter Epithelproliferationen der Brustdrüse bei der Mastopathia fibrosa cystica lassen sich 2 Bildungsarten des Krebses herausstellen. Sie unterscheiden sich durch den Zeitpunkt der morphologisch erkennbaren Cancerisierung vor oder nach einer Zellproliferation. Sie stimmen darin überein, daß bei beiden Bildungsarten im Beginn ein matrizides (Rössle) Wachstum vorliegt, d. h. ein intraepithelialer Beginn im zunächst unveränderten Muttergewebe. Nach Maßgabe wissenschaftlicher Übereinkunft kann man eine zweiphasische oder eine dreiphasische Entwicklung unterscheiden. Es gibt eine intraepitheliale Zellabartung, bei der morphologisch Cancerisierung und Epithelproliferation zeitlich zusammenfallen (1. Bildungsart). Es gibt eine Zellabartung, bei der morphologisch eine gutartige Proliferation der morphologisch erfaßbaren Cancerisierung vorangeht (2. Bildungsart). Die Cancerisierung ist bei der 1. Bildungsart unabhängig von Zellzahl und Differenzierung, bei der 2. Bildungsart teilweise abhängig von der Zellzahl, aber wiederum nicht von der Differenzierung. Die Befunde bei der Mastopathia fibrosa cystica sprechen für das Vorliegen langdauernder cytostatischer Phasen der so verschiedenen Zellproliferationen und Zelldifferenzierungen.Mit 5 Textabbildungen.Herrn Prof. Dr. Dietrich in Dankbarkeit und Verehrung zum 80. Geburtstag.     

The antigenicity of human hemoglobins

Summary By double diffusion and cellulose acetate membrane immunoelectrophoresis the complexity of the Hb-A, Hb-F antigens and anti-Hb-A antiserum was demonstrated though the anti-Hb-F antiserum contained only 1 antibody against Hb-F. The urea added immunoelectrophoresis which consists of the electrophoretical separation of subunit chains on the cellulose acetate membrane under the existence of 8 m urea and the application of antiserum after the removal of urea was used to investigate the antigenicity of hemoglobin subunit chains. In spite of the complexity of system used, 2 lines, for the fast moving -chain and for the slow moving -chain, were demonstrated in anti-Hb-A antiserum and Hb-A system. Also the -chain line in anti-Hb-A antiserum and Hb-F system and the -chain line in anti-Hb-F antiserum and Hb-F system were demonstrated.

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Zusammenfassung Mit der Doppeldiffusion und der Immunoelektrophorese mit der Zellulose-Acetat-Membran wurde die Kompliziertheit der Hb-A, Hb-F-Antigene und des Anti-Hb-A-Antiserums nachgewiesen, obwohl im anti-Hb-F-Antiserum nur ein Antikörper gegen Hb-F enthalten war. Die Antigenität der Hämoglobin-Ketten wurde mit der Harnstoff-Immunoelektrophorese untersucht. Die elektrophoretische Trennung erfolgte auf einer Zellulose-Acetat-Membran unter Einfluß von 8 m Harnstoff und Hinzufügen der Antiseren nach der Entfernung des Harnstoffs. Trotz der Kompliziertheit des benutzten Systems wurden 2 Linien, eine für die schnell wandernde -Kette-und eine für die langsamere -Kette, im Anti-Hb-A-Antiserum und Hb-A-System nachgewiesen. Die Linie der -Kette im Anti-Hb-A-Antiserum und Hb-F-System und die Linie der -Kette im Anti-Hb-F-Antiserum und Hb-F-System wurden auch demonstriert.

     

Calcium-antagonists and islet function. IV. effect of D600

Summary D600 (2 to 20 M;-isopropyl- [(N-methyl-N-homoveratril)--aminopropyl]-3,4,5 -trimethoxyphenyl-acetonitril) caused a dose-related, rapid and reversible inhibition of glucose-induced insulin release. It also suppressed the insulinotropic action of a sulphonylurea but failed to affect the enhancing action of theophylline upon glucose-induced release. The inhibitory effect of D600 was enhanced at low extracellular Ca²⁺ concentration. D600 reduced both basal and glucose-stimulated⁴⁵calcium net uptake, whilst failing to affect the efflux of⁴⁵calcium from perifused islets. The recognition of glucose by the B-cell was also unaffected by D600 as judged by the effect of the sugar upon both 45 calcium efflux and net uptake in the isolated islets. These findings are compatible with the hypothesis that the primary mode of action of D600 is to inhibit Ca²⁺entry in the B-cell.(-isopropyl- [(N-methyl-N-homoveratril)--aminopropyl]-3, 4, 5-trimethoxyphenyl-acetonitril)     

Compound heterozygosity for a β∘-thalassemia (frameshift codons 38/39; -C) and a nondeletional swiss type of HPFH (A→C at NT -110, Gγ) in a Czechoslovakian family

Summary We have analyzed the levels and composition of the fetal hemoglobin (Hb F) in several members of a Czechoslovakian family with a heterozygosity for a newly discovered -thalassemia (codons 38/39; -C), or for a newly detected nondeletional hereditary persistence of fetal hemoglobin (a form of Swiss-HPFH with an AC mutation at nucleotide –100 5 to the Cap site of G), or with a compound heterozygosity for these two conditions. The Hb F level in the -thalassemia heterozygotes averaged 0.3% with low G values ( 28%) and relatively high AT values ( 50%), that in the two Swiss-HPFH heterozygotes averaged 0.8% with 95% G, while that of the compound heterozygote was 3.1% with 95% G. The low Hb F levels were determined with a recently published cation exchange high-performance liquid chromatography (HPLC) procedure that is accurate at the 0.1%–0.2% Hb F level [3]. This method, together with a reversed-phase HPLC procedure, made it possible to detect this unusual type of nondeletional G-HPFH and provided the data indicating that the increased Hb F in the compound heterozygote was derived mainly from the chromosome with the HPFH determinant.This study was supported in part by USPHS Research Grant HLB-41544     

γ/δ Receptor-expressing T-cell clones from a cutaneous T-cell lymphoma suppress hematopoiesis

Summary Recently we described a cutaneous T-cell lymphoma expressing the / T-cell receptor [5]. The patient suffering from this lymphoma showed low numbers of myeloid and T cells in peripheral blood, while B and NK cells were relatively increased. In vitro culture of the patient's bone marrow (BM) cells revealed a significant suppression of myeloid/monocyte colony formation (GM-CFU) compared with normal controls. This was not due to infiltration of the BM with lymphoma cells. We speculated that a soluble factor either secreted or induced by the lymphoma cells might be responsible for the marked suppression of hematopoiesis in this patient. From a skin biopsy with infiltrating / T-lymphoma cells we established T-cell clones bearing the / T-cell receptor and resembling the phenotype of the lymphoma cells. The supernatant (SN) of these / T-cell clones reduced the number of colonies in a CFU-GM assay (using normal control BM) in comparison to SN of / T-cell clones established from the same biopsy. This suppression was seen mainly on day 7 of culture and was not neutralized by the addition of placenta-CM. The main mediator of this suppression seems to be IFN-,since it was detectable in high amounts in the SN of these / T-cell tumor clones as well as in the serum of the patient. In addition, anti-IFN- antibodies can reverse the T-cell SN-mediated suppression of CFU-GM. We conclude that high serum levels of interferon-, which is secreted in high amounts from / T-cells grown from a biopsy of a cutaneous lymphoma, can suppress hematopoiesis.Abbreviations TCR T-cell receptor - IFN- interferon- - SN supernatant - placenta CM placenta conditioned medium - BM bone marrow - CFU-GM myeloid/monocyte colony formation - NK cells natural killer cells - Ab antibody M. Wilhelm was supported by theDeutsche Forschungsgemeinschaft (DFG Wi 728-2)     

Morphine and Gastroduodenal Motility

This study investigated the effects ofintravenous morphine on gastric antral and duodenalmotility in healthy volunteers. Intravenous morphine(both infusion and bolus) increased duodenal motility,typically as bursts of contractions similar to phase IIIof the migrating motor complex. Intravenous infusion ofmorphine 40 g/kg/hr rapidly increased duodenalmotility in nine of 10 subjects; in eight it was phase III-like. Intravenous infusion ofnaloxone (40 g/kg/hr) blocked this effect ofmorphine infusion in five of six subjects. Morphinebolus injection (5-20 g/kg) in six subjects (30-42min following a spontaneous phase III) induced furtherduodenal phase III-like activity; also, morphine bolusinjection (5-20 g/kg) in five subjects (30-42 minfollowing a liquid meal) induced duodenal phase III-like activity. Atropine (10 g/kg intravenously)was able to prevent the action of morphine (bothintravenous infusion and intravenous bolus injection) ininducing this phase III-like activity. Theseobservations show: (1) morphine in very low dose is able tostimulate maximal duodenal contractility; (2) themotility response is typically phase III-like; and (3)morphine acts on opioid receptors to initiate this phase III-like activity, with the effectblocked by antimuscarinic drugs.     

Plasminogen activator induction and platelet aggregation by phorbol and some of its derivatives: Correlation with skin irritancy and tumor-promoting activity

Summary Phorbol and eight of its derivatives were investigated for their ability to stimulate the synthesis of the enzyme plasminogen activator in cultured chick embryo fibroblasts and to aggregate human blood platelets and have been assayed for tumor, promoting and skin, irritant activities. Over a range of concentrations, elevation in the levels of plasminogen activator activity induced by phorbol derivatives correlates well with their promoting and irritant properties. In the platelet aggregation assay however, the parallelism between the activities measured in different biological assays was less complete. While strong promoters, such as TPA, are potent aggregating agents, and weak promoters, such as PDA, are poor or ineffective inducers of aggregation, two derivatives, PDD and PDB, deviate from this general result. Platelets must be exposed to PDD in relatively high concentrations before they will aggregate, and PDB was found to be the most potent aggregating agent of all the derivatives tested.

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Abbreviations TPA 12-O-tetradecanoylphorbol-13-acetate - PDD phorbol-12,13-didecanoate - TPA--oxide 12-O-tetradecanoylphorbol-13-acetate-6,7-oxide - PDB phorbol-12,13-dibenzoate - PDA phorbol-12,13-diacetate - 4-OMe-TPA 4-O-methyl-12-O-tetradecanoylphorbol-13-acetate - 1,2-dihydro-TPA--oxide 1,2-dihydro-12-O-tetradecanoylphorbol-13-acetate-6,7-oxide - 4-PDD 4-phorbol-12,13-didecanoate This work was supported by a Grant-in-Aid from the American Heart Association and with funds contributed in part by the Suffolk Heart Association (Grant 78 747), the National Cancer Institute (Grants CA08290 and CA00118), and the American Cancer Society (Grant PDT1)     

Extrarenal nephroblastomas

Summary The cases of extrarenal nephroblastoma published in the world literature have been tabulated and reviewed, and are discussed from a historical point of view.The Journal of Cancer Research and Clinical Oncology publishes in loose succession Editorials and Guest editorials on current and/or controversial problems in experimental and clinical oncology. These contributions represent exclusively the personal opinion of the author     

Estimation of the malignant potential of gastrointestinal stromal tumors: the value of contrast-enhanced coded phase-inversion harmonics US

Background Recently, contrast agents for ultrasonography (US) such as Levovist have been introduced for routine clinical use. The contrast-enhanced US with Levovist permits evaluation of the intratumoral vascularity of hepatic and pancreatic tumors and is useful for their differential diagnosis. The purpose of the present study was to assess tumor vessels and the parenchymal flow of gastrointestinal stromal tumors (GISTs) by contrast-enhanced coded phase-inversion harmonic US and to evaluate whether vascularity is related to the malignant grade of the GISTs.Methods Thirteen patients with GISTs were included in the present study. Tumors were observed in a real-time fashion of contrast-enhanced coded phase-inversion harmonic US after the injection of Levovist (400mg/ml). The vascular patterns were compared with tumor size, histological diagnosis, KIT mutations, and clinical findings such as metastasis.Results The contrast-enhanced US images of the GISTs were classified into two types according to the blood flow area of the tumors as seen by real-time continuous imaging of the tumor vessels. The image pattern Poor represented vessels flowing only in the peripheral part of the tumor, and Rich represented abundant vessels flowing from the periphery to the central part of the tumor. According to the contrast-enhanced US images, five GISTs were classified as Poor and the others as Rich. Based on the final diagnosis, all tumors with Poor images were determined to be benign GISTs, and the rest tumors except one with Rich images were determined to be malignant GISTs.Conclusions Contrast-enhanced US image is more closely correlated with the final diagnosis than the histological findings.     

Oligosaccharides accumulated in the bovineβ-mannosidosis kidney

Summary The phenotype of bovine-mannosidosis (-mannosidase deficiency), recently identified in Salers cattle, is similar to the caprine form of the disease (Abbittet al., 1991). This investigation was designed to characterize accumulated kidney oligosaccharides in bovine-mannosidosis. Oligosaccharides were extracted from the kidney of an affected Salers calf and purified by chromatographic techniques. The amount of accumulating oligosaccharides in 1 g of wet tissue was about 21µmol. Structures of derivatized oligosaccharides were characterized by high-performance liquid chromatography, mass spectrometry, methylation analysis and sequential exoglycosidase digestions. The major accumulating oligosaccharides were Man1-4GlcNAc and Man1-4GlcNAc1-4GlcNAc. Oligosaccharides accumulating in minor amounts were Man1-4GlcNAc1-4Man1-4GlcNAc, Man1-6Man1-4GlcNAc1-4GlcNAc and Man1-4GlcNAc1-4Man1-4GlcNAc1-4GlcNAc. As in caprine-mannosidosis, oligosaccharides with terminal-mannose residues and cleaved as well as uncleaved chitobiose linkages were identified in bovine-mannosidosis kidney. The accumulating oligosaccharides in tissue were thus identical in bovine and caprine-mannosidosis; however, the source of the novel oligosaccharides remains to be determined.     

The efficacy of neuraminidase treatment in studies on red cell aging

Summary An in vitro system was developed to test the propensity of rat erythrocytes (RBC) toward phagocytosis by homologous peritoneal macrophages after in vivo aging or after in vitro surface modification. Old RBC obtained from erythrocyte populations separated into fractions on the basis of their density were found to be phagocytosed to a significantly greater extent than cells obtained from young cell fractions. Neuraminidase treatment of RBC resulted in extensive phagocytosis in comparison to control cells representing the whole population or old cells. Galactose oxidase treatment of neuraminidase treated RBC afforded no protection from uptake by macrophages. In contrast, treatment of RBC with neuraminidase immobilized on Sepharose 4B, leading to removal of up to 25% of the total membrane sialic acid, did not lead to phagocytosis above control values. These results indicate that extreme caution is necessary in the interpretation of experiments in which neuraminidase is utilized to produce simulated aged RBC.     

B cell adrenoceptors and sulphonylurea-induced insulin release in mouse islets

Summary Interactions of tolbutamide and glibenclamide with B cell adrenoceptors have been reported. This study evaluated the possible role of such interactions in the stimulation of insulin release. Mouse islets were incubated in the presence of 10 mmol/l glucose alone or with tolbutamide (10 mol/l) or glibenclamide (0.02 mol/l). At 0.01–10 mol/l, blockers of ₂-adrenoceptors (yohimbine, idazoxan) or ₁-adrenoceptors (prazosin) had practically no effect on glucose-induced insulin release and did not affect its potentiation by sulphonylureas, except for a slight increase by 10 mol/l prazosin and idazoxan. Nonspecific -blockers (phentolamine, dihydroergotamine) increased control release at 10 mol/l, but only the latter amplified the response to tolbutamide. Blockers of -adrenoceptors were tested at 0.1–100 mol/l: propranolol (₁, ₂), metoprolol (₁) and compound ICI 118-551 (₂). They increased glucose-induced insulin release at 100 mol/l but variably altered the effect of sulphonylureas. Blockers of adrenoceptors have, thus, no effect on insulin release in vitro at therapeutic concentrations. At high concentrations, they non-specifically affect the action of sulphonylureas. We conclude that an interaction with B cell adrenoceptors is not involved in the insulinotropic action of sulphonylureas.